10
QoS
QoS requirements are different for various data types such as streaming
video or music, voice and raw data. To provide higher QoS for streaming
data, priority levels can be set using tags at the beginning of data frames.
Virtual Local Area Network (VLAN) 802.1p priority tags on Ethernet
frames are used to specify 8 (0 – 7) levels of ‘user priority’.
The 200M Powerline AV to Fast Ethernet Adapter allows 4 levels of
Channel Access Priority (CAP (0 – 3)). Therefore, the 8 levels of VLAN
Ethernet tags must be mapped to the 4 levels of CAP priority, where CAP
3 is the highest priority and CAP 0 is the lowest. CAP 3 priority might be
used for voice and network management frames, CAP 2 is used for
streaming video and music while CAP 1 and CAP 0 are used for data.
Mapping VLAN tags or TOS bits to CAP levels is easily done using the
VLAN Priority Mapping function on the QoS tab window.
Device Selection
Select the device from the drop down list and configure the device
selected.
11
List View
The QoS tab includes two list views to provide simple channel access
priority (CAP) classification for individual MAC addresses and IP Ports.
There is a collective limit of eight across both lists. No delimiters, colons,
or dashes are allowed in the MAC address format.
Priority Mapping
The ‘Priority Mapping’ group contains both VLAN and TOS Bit
mapping capability. When selected, packets matching the VLAN or TOS
Bit priority will be assigned the Powerline contention priority (Channel
Access Priority, CAP) as set in the corresponding dropdown box. If a
packet has both VLAN and TOS in it, VLAN will override TOS.
Default CAP
The ‘Default CAP’ group allows for default priority mapping of packets
that do not have a VLAN or TOS bit. Settings are available for Unicast
(directed to a host).
•
IGMP - (default CAP 3) - sets the channel access priority for IGMP
frames - these are the group management frames, not the stream data
•
Unicast - (default CAP 1) - sets the default channel access priority
for unicast frames not matching any other classification or mapping.
•
IGMP managed Multicast Stream (default CAP 2) - sets the default
channel access priority for stream data belonging to a snooped IGMP
multicast group.
•
Multicast/Broadcast - sets the default CAP1 for multicast frames not
in a snooped group and for broadcast frames.
